The trend around here recently has been to hold puppy classes for small breeds separately from the medium and large breed dogs. The cut off for puppy classes is 5 months. After that, you are enrolled in basic obedience. Some of the larger breeds are pretty big by 5 months! You must be so proud of your big "galug!" I'm glad that woman wasn't put off after seeing your boy interact so nicely with the other doggies.